Ch 19 - Air Pollution

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19
Air Pollution
Atmosphere

Atmospheric Composition
 Nitrogen
78.08%
 Oxygen 20.95% *
 Argon 0.93%
 Carbon dioxide 0.04% *
 Other gases & pollutants
 Much

lower conc.
Ecosystem services
 Blocks
UV radiation
 Moderates the climate
 Redistributes water in the hydrologic cycle
Air Pollution - Terminology

Air Pollution
 Chemicals
added to the atmosphere by natural events
or human activities in high enough concentrations to be
harmful

Two categories
 Primary
Air Pollutant
 Harmful
substance emitted directly into the atmosphere
 Secondary
 Harmful
Air Pollutant
substance formed in the atmosphere when a
primary air pollutant reacts with substances normally found in
the atmosphere or with other air pollutants
Major Classes of Air Pollutants







Particulate Material
Nitrogen Oxides
Sulfur Oxides
Carbon Oxides
Hydrocarbons
Ozone
Lead
Major Air Pollutants
Two main human sources
of primary air pollutants
- Industry
- Transportation
Particulate Material

Particulate Matter
 Solid
or liquid particles suspended in air
 soil
particles, soot, lead, asbestos, sea salt, & sulfuric acid
droplets

Dangerous
 May
contain materials with toxic/carcinogenic effects
 Small particles can become lodged in lungs
Nitrogen & Sulfur Oxides

Nitrogen Oxides
 Gases
produced by the chemical interactions between
atmospheric nitrogen and oxygen at high temperature
 Greenhouse gases that cause difficulty breathing

Sulfur Oxides
 Gases
produced by the chemical interactions between
sulfur and oxygen
 Causes acid precipitation
Carbon Oxides & Hydrocarbons

Carbon Oxides
 Gases
carbon monoxide (CO) and carbon dioxide (CO2)
 Greenhouse gases

Hydrocarbons
 Organic
compounds that contain only hydrogen &
carbon (ex: CH4 - methane)
 Some are related to photochemical smog & greenhouse
gases

Photochemical smog - It is the chemical reaction of sunlight,
nitrogen oxides and hydrocarbons in the atmosphere
Formation of Photochemical Smog
© 2012 John Wiley & Sons, Inc. All rights reserved.
Urban Air Pollution

Photochemical Smog (ex: Los Angeles below)
 Brownish-orange
haze formed by chemical reactions
involving sunlight, nitrogen oxide, and hydrocarbons
Pollution is linked to:
Immune system sup.
Inf. of respiratory track
Chronic bronchitis
Increased drowsiness
Impaired reflexes
Ozone

Tropospheric Ozone (Bad)
 Man-made
pollutant in the lower atmosphere
 Secondary air pollutant
 Component of photochemical smog

Stratospheric Ozone (Good)
 Essential
component that screens out UV radiation in
the upper atmosphere
 Man- made pollutants (ex: CFCs) can destroy it
Ozone Damage to Grape Leaves
Sources of Outdoor
Air Pollution

Affects ozone
in So. Cal.
Two main sources
High temps
 Transportation
Hydrocarbons
Sunlight & water vapor
 Industry
Sources of Smog
in Los Angeles
Effects of Air Pollution

Low level exposure
 Irritates
eyes
 Causes inflammation of respiratory tract

Can develop into chronic respiratory diseases

Greater health threat to children than adults
 Air
pollution can restrict lung development
 Children breath more often than adults
 Children who live in high ozone areas are more likely to
develop asthma
Controlling Air Pollution

Smokestacks w/ electrostatic precipitator
Electrode imparts negative charge on the air
pollutants
 Negatively charged pollutants are then
attracted to positively charged walls & fall into
collector


Smokestacks w/ scrubbers

Water or other fluid to dissolve particulates
then the water is sent through a filter
Both are primarily used
to remove particulate matter
Scrubbers
Emissions not controlledheavily polluted
Emissions controlled with
scrubbers-only steam
expelled
Controlling Air Pollution

Phase I Vapor Recovery System for gasoline
The Clean Air Act

Authorizes EPA to set limits on amount of specific air
pollutants permitted

Focuses on 6 pollutants:
 lead,
particulate matter, sulfur dioxide, carbon monoxide,
nitrogen oxides, & ozone

Act has led to decreases in air pollutants
 Most
dramatic is lead - decreased by 98% since 1970
(due to switch to unleaded gasoline)
Ozone Depletion in Stratosphere

Ozone Protects earth from UV radiation
Ozone Depletion in Stratosphere

Ozone (O3) thinning/hole
 First
identified in 1985 over
Antarctica
 a steady decline of about 4% per
decade in the total volume of
ozone

Caused by human-produced
bromine and chlorine
containing chemicals
(Ex: CFCs)
Ozone Depletion

Hole over Antarctica requires two conditions:
 Sunlight
 Circumpolar
a

vortex
mass of cold air that circulates around the polar region
Effects of Ozone Depletion
 Higher
levels of UV-radiation hitting the earth
 Eye
cataracts
 Skin cancer


May disrupt ecosystems
May damage crops and forests
Recovery of Ozone Layer

Montreal Protocol (1987)
 Reduction
of CFCs
 Started using HCFCs (greenhouse gas)

Phase out of all ozone destroying chemicals
 This
is underway globally

Satellite pictures in 2000 indicated that ozone
layer was recovering

Full recovery will not occur until ~2050
Acid Deposition

Sulfur dioxide & nitrogen dioxide emissions react
with water vapor in the atmosphere & form acids
that return to the surface
pH scale
How Acid Deposition Develops
Effects of Acid Deposition


Declining Aquatic Animal Populations
Thin-shelled eggs prevent bird reproduction
 Calcium

is unavailable in acidic soil
Forest decline
 Black
Forest in Germany
Acid Deposition and Forest Decline
© 2012 John Wiley & Sons, Inc. All rights reserved.
Lead (Pb) in the Air


Metal found naturally in the environment as well as
in manufactured products.
“Back in the day” Major source of Pb in the air:
 Cars



and trucks
As a result the EPA banned Pd from gasoline
Since the ban 95% < in lead emissions
Today the highest levels of Pd emissions are:
 Ore
& metals processing
 piston-engine aircraft operating on leaded aviation
gasoline
Exposure to Lead (Pb) in the Air

Causes
 Behavior
problems
 Headaches
 Hearing problems
 Permanently reduced cognitive abilities

Effects the - nervous system, kidney function,
immune system, reproductive and developmental
systems and the cardiovascular system
 Children
are more sensitive to low levels of exposure
Air Pollution Around the World

Air quality deteriorating rapidly in developing
countries
 Have
older cars
 Don’t generally have scrubbers (expensive)

Some of the worst cities in world
 Beijing,
China
 Calcutta, India
 Mexico City, Mexico
 Shanghai, China
 Shenyang, China
 Tehran, Iran
Some of these cities
residents only see
sunlight a few weeks
each year
Case-In-Point Air Pollution in Beijing
and Mexico City
Beijing
Mexico City
Long Distance Transport of Air Pollutants
(Pollution - not just a local issue)
Global
Distillation
Effect
Indoor Air Pollution

Pollutants can be 5–100x greater than outdoors

Radon, cigarette smoke, carbon monoxide, nitrogen
dioxide, formaldehyde pesticides, lead, cleaning
solvents, ozone, and asbestos
Indoor Air Pollution /
Radon
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